内蒙古草原火灾损失评估方法研究

文章利用环境减灾卫星资料与地面调查相结合的方法,以2012年锡林郭勒盟一起特大草原火灾为例,精确界定草原火灾的过火面积;运用价值评估和价值替代法,建立草原火灾直接和间接经济损失评估方法,全面评估草原火灾造成的损失以及对环境的危害程度,为草原火灾后的恢复生产提供决策依据。     

MODIS数据在南方丘陵地区局地森林火灾面积评估中的应用研究

根据2004年的MODIS数据和森林火灾地面调查数据, 以福建省为例, 来探讨典型南方丘陵山区森林火灾发生后火灾面积大小评估的技术方法。在对火区250 m分辨率MODIS数据特征分析的基础上, 通过MODIS近红外通道反射率和归一化植被指数在火灾发生前后的散点图, 结合火区的假彩色合成影像, 利用ENVI软件的ROI处理功能建立火灾面积评估技术方法。对35起森林火灾样本进行评估, 过火面积总体估算误差为15 hm2, 结果表明, 在南方丘陵山区, 应用MODIS数据开展森林火灾面积评估, 能较好地满足业务需求。     

森林火险气象指数及其构建方法回顾

森林火灾是威胁地球生态的主要灾害之一。为实现对林区起火可能性大小、火灾强度、火灾蔓延速度以及火灾扑救难易程度进行评估和预测，国内外专家学者利用森林火灾与气象条件之间的关系研制了诸多森林火险气象指数的构建方法。作者对近几十年来国内外森林火险气象指数的研究工作进行回顾和总结，得出广泛应用的火险指数可以归纳为指数查对法、综合指标法和统计回归法等3种类型，究其原理和使用效果，各有优缺点。在实际使用过程中，需要结合我国的气候和环境特点进行适用性修正和完善。     

基于层次分析法的黑龙江省森林火灾气象风险评估

本文从森林火灾的危险性、易损性和防灾减灾能力出发,采用层次分析法对森林火灾的气象风险进行了评估研究。可应用于森林火灾气象服务,实现灾前、灾中、灾后风险动态评估。研究发现:当气象条件相同时,森林火灾的风险主要由易损性和抗灾能力决定,高风险区的分布与二者有着直接关系,即主要分布在大兴安岭、伊春、哈尔滨、牡丹江一带。是森林覆盖率较高或者经济相对较发达的地区,这些地区一旦发生森林火灾,损失相对较大。     

基于MODIS地表覆盖(LC)的森林火灾识别方法

通过分析MODIS多光谱地表覆盖产品,证明MODIS本身具有精确识别包括5种森林在内的IGBP 17种地表类型的能力,完全可以满足识别森林火灾的实际需要.在此基础上提出基于MODIS地表覆盖的森林火点识别方法,探讨使用MODIS地表覆盖数据识别森林火灾的数据处理操作过程.应用该森林火点识别方法,MODIS实时广播接收站可以建立一套由MODIS火点侦测模块和MODIS森林火点识别模块构成的完全基于自身数据的森林火灾监测系统.5种森林地表整体平均识别误差为3.5%,可以满足卫星遥感森林火灾监测系统要求.     

连云港市森林火灾发生特点及火险预报方法的研究

通过对连云港市１９８７－１９９３年大小和程度不同的１１１次森林火灾查找原因并进行天气分析,指出原全国森林火险天气等级方法的不合理部分,并加以改进,增加了实效雨量、积雪深度等因素,推导出比较符合实际的森林火险天气等级预报方法。通过１９９４－１９９６年的４５次森林火灾验证,准确率提高达９％。     

森林火灾与气象

森林的毁坏主要来自三方面:乱砍滥伐、森林火灾和病虫害蔓延.其中,森林火灾是森林保护的大敌.它发生次数多,蔓延速度快,毁林面积大、扑救难度大.因此,防御森林火灾是林区的头等大事.众所周知,燃烧是一种物理过程,它决定于物质与环境的温度、湿度、氧气供给与风速.森林火灾的发生次数多少与强度大小也不例外.森林火灾的发生和蔓延,除了与森林的种类、疏密程度、树木年龄、森林中或荒野的杂草种类以及复盖面积和厚度有关     

用NOAA卫星信息估算过火面积初探

森林、草原是宝贵的自然资源。今年4、5月份发生了西伯利亚森林大火、蒙古草原大火、我国境内的内蒙古森林草原大火等多场大火灾。火灾烧毁大量的森林、牧草和生产、生活设施．危及人民生命，严重破坏了生态环境。所以对火灾的动态监测及灾后评估有极其重要的意义。     

森林火灾对林地小气候的影响

通过对1987年内蒙古大兴安岭特大森林火灾迹地小气候的考察和分析,找出了不同火灾区气象要素的变化特征,从中发现林地小气候的变化与森林火灾程度相关。轻、中度火灾区小气候逐渐与未烧林区一致;重度火灾区小气候与林窗或空旷地接近。重火灾区范围较小,随着森林植被的迅速恢复,其气候状况也将逐步改善。     

惠州市森林火灾的气象分析和短期火险预报

本文通过对惠州市所属区域内１９８８～１９９７年的森林火灾（包括森林火警）资料进行普查,并对其相应的气象要素进行对比分析,发现在火源条件不变的情况下,气象要素的变化,特别是湿度的变化,与林火的发生、发展存在必然的联系。用林火记录和气象要素建立线性回归预报方程,预报短期森林火灾发生的天气等级,为发布森林火险预报提供依据。１　森林火灾的气象条件分析１－１　森林火灾与气候的关系在火源不变的情况下,森林火灾的发生发展,主要取决于植物干燥程度,即植被的含水量,植被的含水量又取决于当年的降雨量和降雨日数。雨量…     

大兴安岭气候干湿变化及对森林火灾的影响

明确气候变化背景下大兴安岭林区气候干湿状况特征,揭示其对森林火灾的影响,可为该区域森林火灾管理和森林资源保护提供科学依据。基于大兴安岭林区1974—2016年标准化降水指数（SPI）,采用统计分析和对比分析方法,系统研究不同干湿情景对森林火灾发生次数及过火面积的影响,并讨论不同等级干旱对其影响的异同性。结果表明:1974—2016年,年、季尺度上大兴安岭林区气候均呈湿润化趋势。森林火灾发生次数多（少）和过火面积大（小）与气候的干湿状况（等级）基本一致,但森林火灾的发生次数与气候干湿状况相关更为密切。年尺度上,SPI与火灾次数呈负相关,与过火面积的自然对数则呈较弱的负相关;季尺度上,各季节SPI与对应的林火次数和过火面积自然对数均呈显著的负相关,但与过火面积的相关程度差异较大,以春季相关最为显著,秋季次之,夏季则相对较弱;不同季节SPI与年林火次数和过火面积自然对数呈负相关,前一年冬季SPI对当年火灾次数的贡献最大。可见,气候干湿状况对森林火灾的影响存在明显的滞后效应。SPI不仅能较好地反映区域气候的干湿状况,亦能较好地指示森林火灾发生的可能性及发生火灾的过火面积的相对变化情况,可为森林火灾预测和管理提供科学依据。     

Analysis of lightning-induced forest fires in Austria

Besides human-caused fires, lightning is the major reason for forest fire ignition in Austria. In order to analyse the causes of ignition and to characterise lightning-induced forest fires, fire records were compared with the real appearance of lightning events by using the Austrian Lightning Detection and Information System for the period from 1993 to 2010. A probability was estimated for each forest fire being caused by lightning by using a decision tree and decision matrices based on flash characteristics (e.g. amplitude, time, location). It could be shown that 15 % of documented forest fires were lightning-caused. Nearly all lightning-caused fires were found during the summer months, whereas almost 40 % of all fires occurring from June to August were naturally caused. Most lightning-caused fires took place in the south and east of Austria. Lightning fires were more frequent at higher altitudes and primarily affected conifer forests. The median burned area was lower than that for anthropogenic forest fires.     

Estimating emissions from forest fires in Thailand using MODIS active fire product and country specific data

Studies on air pollution and climate change have shown that forest fires constitute one of the major sources of atmospheric trace gases and particulate matter, especially during the dry season. However, these emissions remain difficult to quantify due to uncertainty on the extent of burned areas and deficient knowledge on the forest fire behaviours in each country. This study aims to estimate emissions from forest fires in Thailand by using the combination of the Moderate Resolution Imaging Spectroradiometer (MODIS) for active fire products and country-specific data based on prescribed burning experiments. The results indicate that 27817 fire hotspots (FHS) associated with forest fires were detected by the MODIS during 2005–2009. These FHS mainly occurred in the northern, western, and upper north-eastern parts of Thailand. Each year, the most significant fires were observed during January–May, with a peak in March. The majority of forest FHS were detected in the afternoon. According to the prescribed burning experiments, the average area of forest burned per fire event was found to fall within the range 1.09 to 12.47 ha, depending upon the terrain slope and weather conditions. The total burned area was computed at 159309 ha corresponding to the surface biomass fuel of 541515 tons dry matter. The forest fire emissions were computed at 855593 tons of CO₂, 56318 tons of CO, 3682 tons of CH₄, 108 tons of N₂O, 4928 tons of PM_2.5, 4603 tons of PM₁₀, 357 tons of BC and 2816 tons of OC.     

Management alternatives to offset climate change effects on Mediterranean fire regimes in NE Spain

Fire regime is affected by climate and human settlements. In the Mediterranean, the predicted climate change is likely to exacerbate fire prone weather conditions, but the mid- to long-term impact of climate change on fire regime is not easily predictable. A negative feedback via fuel reduction, for instance, might cause a non-linear response of burned area to fire weather. Also, the number of fires escaping initial control could grow dramatically if the fire meteorology is just slightly more severe than what fire brigades are prepared for. Humans can directly influence fire regimes through ignition frequency, fire suppression and land use management. Here we use the fire regime model FIRE LADY to assess the impacts of climate change and local management options on number of fires, burned area, fraction of area burned in large fires and forest area during the twenty-first century in three regions of NE Spain. Our results show that currently fuel-humidity limited regions could suffer a drastic shift of fire regime with an up to 8 fold increase of annual burned area, due to a combination of fuel accumulation and severe fire weather, which would result in a period of unusually large fires. The impact of climate change on fire regime is predicted to be less pronounced in drier areas, with a gradual increase of burned area. Local fire prevention strategies could reduce but not totally offset climate induced changes in fire regimes. According to our model, a combination of restoring the traditional rural mosaic and classical fire prevention would be the most effective strategy, as a lower ignition frequency reduces the number of fires and the creation of agricultural fields in marginal areas reduces their extent.     

The Impact of Climate Change on Wildfire Severity: A Regional Forecast for Northern California

We estimated the impact of climatic change on wildland fire and suppression effectiveness in northern California by linking general circulation model output to local weather and fire records and projecting fire outcomes with an initial-attack suppression model. The warmer and windier conditions corresponding to a 2 × CO₂ climate scenario produced fires that burned more intensely and spread faster in most locations. Despite enhancement of fire suppression efforts, the number of escaped fires (those exceeding initial containment limits) increased 51% in the south San Francisco Bay area, 125% in the Sierra Nevada, and did not change on the north coast. Changes in area burned by contained fires were 41%, 41% and –8%, respectively. When interpolated to most of northern California's wildlands, these results translate to an average annual increase of 114 escapes (a doubling of the current frequency) and an additional 5,000 hectares (a 50% increase) burned by contained fires. On average, the fire return intervals in grass and brush vegetation types were cut in half. The estimates reported represent a minimum expected change, or best-case forecast. In addition to the increased suppression costs and economic damages, changes in fire severity of this magnitude would have widespread impacts on vegetation distribution, forest condition, and carbon storage, and greatly increase the risk to property, natural resources and human life.     

Modeling the Impact of Black Spruce on the Fire Regime of Alaskan Boreal Forest

In the boreal biome, fire is the major disturbance agent affecting ecosystem change, and fire dynamics will likely change in response to climatic warming. We modified a spatially explicit model of Alaskan subarctic treeline dynamics (ALFRESCO) to simulate boreal vegetation dynamics in interior Alaska. The model is used to investigate the role of black spruce ecosystems in the fire regime of interior Alaska boreal forest. Model simulations revealed that vegetation shifts caused substantial changes to the fire regime. The number of fires and the total area burned increased as black spruce forest became an increasingly dominant component of the landscape. The most significant impact of adding black spruce to the model was an increase in the frequency and magnitude of large-scale burning events (i.e., time steps in which total area burned far exceeded the normal distribution of area burned). Early successional deciduous forest vegetation burned more frequently when black spruce was added to the model, considerably decreasing the fire return interval of deciduous vegetation. Ecosystem flammability accounted for the majority of the differences in the distribution of the average area burned. These simulated vegetation effects and fire regime dynamics have important implications for global models of vegetation dynamics and potential biotic feedbacks to regional climate.     

Impact of climate variability on summer fires in a Mediterranean environment (northeastern Iberian Peninsula)

We analyse the impact of climate interannual variability on summer forest fires in Catalonia (northeastern Iberian Peninsula). The study period covers 25 years, from 1983 to 2007. During this period more than 16000 fire events were recorded and the total burned area was more than 240 kha, i.e. around 7.5% of whole Catalonia. We show that the interannual variability of summer fires is significantly correlated with summer precipitation and summer maximum temperature. In addition, fires are significantly related to antecedent climate conditions, showing positive correlation with lagged precipitation and negative correlation with lagged temperatures, both with a time lag of two years, and negative correlation with the minimum temperature in the spring of the same year. The interaction between antecedent climate conditions and fire variability highlights the importance of climate not only in regulating fuel flammability, but also fuel structure. On the basis of these results, we discuss a simple regression model that explains up to 76% of the variance of the Burned Area and up to 91% of the variance of the number of fires. This simple regression model produces reliable out-of-sample predictions of the impact of climate variability on summer forest fires and it could be used to estimate fire response to different climate change scenarios, assuming that climate-vegetation-humans-fire interactions will not change significantly.     

Determining Effects of Area Burned and Fire Severity on Carbon Cycling and Emissions in Siberia

The Russian boreal forest contains about 25% of the global terrestrial biomass, and even a higher percentage of the carbon stored in litter and soils. Fire burns large areas annually, much of it in low-severity surface fires – but data on fire area and impacts or extent of varying fire severity are poor. Changes in land use, cover, and disturbance patterns such as those predicted by global climate change models, have the potential to greatly alter current fire regimes in boreal forests and to significantly impact global carbon budgets. The extent and global importance of fires in the boreal zone have often been greatly underestimated. For the 1998 fire season we estimate from remote sensing data that about 13.3 million ha burned in Siberia. This is about 5 times higher than estimates from the Russian Aerial Forest Protection Service (Avialesookhrana) for the same period. We estimate that fires in the Russian boreal forest in 1998 constituted some 14–20% of average annual global carbon emissions from forest fires. Average annual emissions from boreal zone forests may be equivalent to 23–39% of regional fossil fuel emissions in Canada and Russia, respectively. But the lack of accurate data and models introduces large potential errors into these estimates. Improved monitoring and understanding of the landscape extent and severity of fires and effects of fire on carbon storage, air chemistry, vegetation dynamics and structure, and forest health and productivity are essential to provide inputs into global and regional models of carbon cycling and atmospheric chemistry.     

Summer convection and lightning over the Mackenzie river basin and their Impacts during 1994 and 1995

Abstract

Lightning activity over the Mackenzie basin has been examined for the summers of 1994 and 1995. In recent years, the lightning network operating in the Northwest Territories has detected an average of 118 K strikes per season. Positive lightning strikes (defined as lightning discharges lowering positive charge to the earth) typically comprise 12% of the total. The lightning activity during 1994 was approximately 20% below normal, while in 1995, it was 53% below normal. However, the fraction of positive lightning strikes was 25.6% during 1995. The lightning was linked to synoptic conditions favouring severe storm development, especially those tied to the diurnal cycle. As a consequence of the lightning, as well as the very dry surface conditions, record forest areas were burned. In the Northwest Territories alone, forest fires burned 3 Mha in 1994 and 2.8 Mha in 1995.     

Present climate trend analysis of the Etesian winds in the Aegean Sea

Wildfires are a common experience in Alaska where, on average, 3,775?km² burn annually. More than 90% of the area consumed occurs in Interior Alaska, where the summers are relatively warm and dry, and the vegetation consists predominantly of spruce, birch, and cottonwood. Summers with above normal temperatures generate an increased amount of convection, resulting in more thunderstorm development and an amplified number of lightning strikes. The resulting dry conditions facilitate the spread of wildfires started by the lightning. Working with a 55-year dataset of wildfires for Alaska, an increase in the annual area burned was observed. Due to climate change, the last three decades have shown to be warmer than the previous decades. Hence, in the first 28?years of the data, two fires were observed with an area burned greater than 10,000?km², while there were four in the last 27?years. Correlations between the Palmer Drought Severity Index and the Canadian Drought Code, against both the number of wildfires and the area burned, gave relatively low but in some cases significant correlation values. Special emphasis is given to the fire season of 2004, in which a record of 27,200?km² burned. These widespread fires were due in large part to the unusual weather situation. Owing to the anticyclonic conditions of the summer of 2004, the composite anomaly of the 500?mb geopotential height showed above normal values. The dominance of a ridge pattern during summer resulted in generally clear skies, high temperatures, and below normal precipitation. Surface observations confirmed this; the summer of 2004 was the warmest and third driest for Interior Alaska in a century of climate observations. The fires lasted throughout the summer and only the snowfalls in September terminated them (at least one regenerated in spring 2005). Smoke from the forest fires affected the air quality. This could be demonstrated by measurements of visibility, fine particle matter, transmissivity of the atmosphere, and CO concentration.